Hyperbolic cosine function help?

I have a maths assignment and one of the questions is as follows:
task 3 M&P
the nose of the skin is constructed in outer layers. an outer skin for strength, and an inner layer of composite material.
(here is a graph with no details except the width of the inner function 48 3/4 inches, and the height of the inside function 48 3/4 inches.

the following function is proposed for the nose: y= 142.3-15.25cosh(0.0438x)

decide if the function is reasonable as a mathematic model for the nose, detailing the functions significant features with full graphic and mathematical support. explore the stewnghts and limitations of the model.

that's my maths assignment "hard to start question". please help me and show all working where possible, if you can.